Raymond,

 

For a high-pressure fuel pump that generates a large volume of fuel flow, a 1/4“ return line seems a bit small to me.  If you attach a fuel pressure gauge to a “T” midway in the ¼” return line and run fuel through your pump and out the return line (past the pressure gauge), when the return line is big enough to handle the flow, then you will see almost no build up in pressure.  If the line is too small, then the inability of the fuel to easily escape through the return line will cause a build-up of pressure in the gauge.  The amount may be negligible or it may be a lot, depending on the force of the fuel.  Ideally, the pressure on the return line would be zero, or close to it.  Use a return line that generates little or no pressure on the fuel pump.

 

Bob

 

 

I am about to put the fuel tank in my first wing. I have to weld a flange on it for the fuel return line. Anyone can tell me if a 1/4" fuel return line is large enough ????

Raymond